A precursor is not going to cost 50 gold. My guess, since they love to "use a stack of this and a stack of that", a stack of deldrimore steel would be a KITTEN of a project.
I honestly think it WON'T require that as those are T7 materials that are associated with ascended gear. It would seem weird for those to be used to create a weapon that is an exotic.
I'm guessing it's going to require large amounts of other equally expensive items; 250 of each T6, 250 of multiple lodestones, 250 giant eyes, etc. If they want to time gate it, we still have charged quartz which is a T6.